FIG. 32 is a schematic view showing a conventional apparatus for casting metal with a mold 1. The mold 1 comprises a lower mold member 4 serving as a cooling plate, a side mold member 2 disposed on the lower mold member and an upper mold member 3 having an upper wall 31. The inner surface of the side mold member 2 is a generally hollow cylindrical surface with a diameter increased downward, specifically sloped at not more than 5° (i.e., a sloped surface for facilitating removal of a cast ingot). The lower surface of the upper mold member 3, the inner surface of the side mold member 2 and the upper surface of the lower mold member 4 define a casting chamber 5. The upper surface of the upper mold member 3 and the inner surface of the upper wall 31 define a molten metal reservoir 51 that is for storing molten metal M teamed from, for example, a melting furnace (not illustrated). Thus, the bottom of the reservoir 51 is the upper surface of the upper mold member 3. A mortar-shaped molten metal inlet (sprue) 7 is provided in the center portion of the upper mold member 3.
The upper surface of the side mold member 2 is fitted to the lower surface of the upper mold member 3 by means of non-illustrated predetermined fitting means, such as fitting screws.
The sprue 7 is opened and closed by an opening/closing plug 8. When the plug 8 is moved upward by means of a non-illustrated plug-driving apparatus, the sprue 7 is opened, and the molten metal M is teemed into the casting chamber 5. When the plug is moved downward by means of the plug-driving apparatus, the sprue 7 is closed, and teeming of the molten metal M into the casting chamber is stopped.
The cooling plate (lower mold member) 4, side mold member 2, bottom of the molten metal reservoir 51 (upper mold member 3) and plug 4 constitute the mold 1 for casting a columnar ingot C having generally flat, parallel, upper and lower surfaces.
Beneath the cooling plate 4 is disposed a spray nozzle 6 for spraying water to the lower surface of the cooling plate 4 to thereby cool the cooling plate 4. The spray nozzle 6 is fixedly accommodated in a hollow cylindrical case 63 that includes a drain outlet 64 for discharging the cooling water used and supports thereon the cooling plate 4 that is separated from the side mold member 2 before use of the metal-casing apparatus.
Around the mold 1 is disposed an electric furnace 53 for maintaining the temperature of the molten metal M teemed into the casting chamber 5 at a predetermined temperature in order to prevent the molten metal M from being cooled by the side wall of the mold 1.
Above the upper wall 31 of the upper mold member 3 is disposed an upper lid 61 for closing the upper portion of the molten metal reservoir 51, that includes a through-hole 62 through which the plug 8 is inserted.
Casting of the ingot C will next be described.
Firstly, the cooling plate 4, spray nozzle 6 and hollow cylindrical case 63 are moved upward by means of a non-illustrated lower mold member (cooling plate) driving apparatus, closing the lower portion of the side mold member 2 with the cooling plate 4.
Subsequently, the opening/closing plug 8 is moved upward by means of the non-illustrated plug-driving apparatus. After the molten metal M is teemed into the casting chamber 5 through the sprue 7 and the casting chamber 5 is filled with the molten metal M, the plug 8 is moved downward by means of the plug-driving apparatus to thereby close the sprue 7.
Subsequently, water is sprayed from the spray nozzle 6 onto the lower surface of the cooling plate 4 to thereby cool and solidify through the cooling plate 4 the molten metal M unidirectionally, i.e. from the lower portion of the side mold member 2 to the upper portion thereof (the surface of the plug 8 forming a part of the casting chamber 5), so that the solidification interface in the molten metal M is not closed.
When the molten metal M is cooled and solidified as described above, the metal M shrinks through solidification.
After the molten metal M is cooled to form a cast ingot C, the cooling plate 4, spray nozzle 6 and hollow cylindrical case 63 are moved downward by means of the cooling plate-driving apparatus. As a result, the cooling plate 4 on which the cast ingot C is placed is detached from the side mold member 2, whereby the cast ingot C can be removed from the cooling plate 4.
Cast ingots C can be produced sequentially in a manner similar to that described above.
JP-A HEI 9-174198 discloses an ingot-casing apparatus similar to the aforementioned metal-casting apparatus.
A conventional mold for casting metal is used for casting a columnar ingot having generally flat, parallel, upper and lower surfaces.
When the cast ingot is forged into a product having a complicated shape, the ingot is not subjected to satisfactory plastic forming in a forgoing mold having a complicated shape, since the ingot has substantially flat upper and lower surfaces. Therefore, since the ingot cannot be formed into such a product through a single forging operation, the ingot must be subjected to preliminary shaping.
Therefore, there has been a demand for a cast ingot that can be forged through a single forging operation into a product having a complicated shape.
The present invention contemplates realizing the aforementioned demand, and a first object of the present invention is to provide a metal-casting apparatus enabling a mold of a complicated shape for producing a three-dimensionally profiled cast ingot to be provided with ease at low cost, the cast ingot to be easily subjected to forging which is the step subsequent to casting, and to provide a method for casting metal using the metal-casting apparatus.